This invention relates to luminaire duration controls the photoelectric cell actuated devices such as street lights, outdoor advertising, highway signs, etc.
More particularly, this invention relates to a duration control which is compatible with existing photoelectric cell actuated luminaires and the like.
Many luminaires and other type of street lights are controlled by photoelectric cells which dictate the operating or burning hours of the luminaires. More specifically, when dusk approached, the reduced daylight caused the photoelectric cell to close its associated electrical relay and complete a circuit. When the circuit was completed, a power source activated the associated luminaire or luminaires, all in a manner well known in the art. When sufficient light at dawn was received by the photoelectric cell, its associated electrical relay opened, thereby preventing the source from activating the luminaire or luminaires.
Presently used photoelectric cell actuated relay systems result in their associated luminaires being activated for a frequently longer period of time than necessary after daylight. This, of course, when multiplied by the vast number of luminaires, highway signs, etc., controlled by such photoelectric cell actuating devices, amounts to a vast waste of energy. Thus, there is a need for a luminaire duration control device or system which is compatible with existing photoelectric cell actuating systems and has the additional feature of terminating the activation of the associated luminaire, a predetermined time prior to the normal shut-off by the photocell. This duration control system must operate in a simple straightforward, reliable manner without requiring constant maintenance or adjustment and without requiring a comparative amount of energy to accomplish the same.